Why verify it, the fact that Jillian was a barbarian was proof as it was.
Her status was proof that the city was destroyed, and the last report places the blame on a large flight of dwagons... going to the ruins would have been pointless; she'd find nothing but ruins and they would provide her no leads to the leader of the dwagons
Their neighbors have also never found the cities themselves... a master class foolamancer, Jack, was the ONLY reason those cities were never discovered... without him their, nothing was hiding FAQ anymore and it would have been discovered by the vampires... that's the biggest problem with your theory... you point out them not finding the ruins, but at the same time overlook the fact that it would be 100x's easier to spot full functioning citiesAdd to that the fact that in the time since FAQ was supposedly destroyed, their TV neigbors (in fact, no one) haven't run across any ruins. You'd think that unless there was a total annihilation of the populace, there would be refugees / survivors carrying tales, or at least rumors.
As for ruins, you know nothing about what would remain of a city... for all you know, a city that is destroyed is reduced to level 0; which likely means no buildings or anything... this in turn would not make it easy to spot as there would be barely anything left... Transyvito units may have passed by close enough to see the cities, but not necessairly directly over or close enough to see an empty plot... that's why they need to go out their and check for it as they can not see it from where ever they are
AS for the survivors... taking out the possibility that Stanely didn't just wipe them all out, if Jillian did not keep paying their upkeep, survivors would have been disbanded... but considering Stanely wanted to use FAQ as his escape, it is likely that he would indeed want to throughly wipe them all out
For one thing, we don't know WHNE he started his quest as he could have started AFTER faq... back when he did still have 11 cities.I just can't see someone as rash and brash as Stanley taking out 3 cities simultaneously without bragging about his military prowess to anyone unlucky enough to be in the same room with him. And given that he's lost 11 cities since he began the Quest for the Arkentools, I seriously don't see him as having the moxie to have wiped out 3 cities in a single turn. Especially since his staff of casters was supposed to have increased by a croakamancer and foolamancer after his supposed conquests . . . you'd think that they would increase his effectiveness, not dimimish it.
Second of all, Faq was practically defenseless; that explains how Stanely was able to destroy all 3 cities in one turn... it was a city that practiced pacifism to the point that Jillian said their soldiers could be more described as clerks... it seems the only units that could fight were the mercenaries which were always out in the field with jillian... without them, Faq is pretty much defenseless